Generally, an electric/electronic device refers to a device designed to perform a predetermined function (or functions) through a combination of electric/electronic parts. The mobile communication terminal, which is one of the most popular electric/electronic devices, is essentially a device designed to enable a mobile user to telecommunicate with a receiver who is remotely located. Thanks to scientific development, however, the latest mobile communication terminals have functions, such as camera and multimedia data playback, in addition to the basic functions, such as voice communication, short message service, and address book.
As such, the device performing multiple functions (i.e. the main function and additional functions) comprises a plurality of processors. In other words, one or more application processors, which control and perform additional functions, and a main processor, which controls the overall operation of the device and the operation of the application processor, can be comprised. For example, for a mobile communication terminal that processes an image signal, the main processor controls the communication function as well as the overall operation of the mobile communication terminal, and the application processor controls the processing of the image signal, under the control of the main processor.
Other than the mobile communication terminal described above, there can be a variety of portable terminals, such as personal digital assistants (PDA) and portable multimedia players (PMP), which comprise a plurality of processors to perform multiple functions. Here, portable terminals refer to electronic devices that can be easily carried by making the size compact in order to perform functions such as game and mobile communication.
Having an electric/electronic device perform multiple functions requires one or more storage devices for storing data and information required for the functions. Common storage devices include NAND flash memories and SD (Secure Digital) cards. The NAND flash memory is directly coupled to the phone board of a mobile communication terminal, and thus it is not possible to be removed by the user. On the other hand, the SD card can be removed by the user since the socket is mounted on the phone board.
An internal system of a device having a plurality of processors and a plurality of memories is illustrated in FIG. 1 and FIG. 2.
FIG. 1 is a diagram showing a device, in which a plurality of memories are used, and FIG. 2 is a block diagram outlining an application processor in accordance with the prior art.
As shown in FIG. 1, in the device for performing multiple functions, a main processor 110 and an application processor 120 are coupled through a bus, which is for communicating data and/or information, and the application processor 120 is coupled to one or more memories. A bus refers to a common-purpose electrical route, used for the communication of information between processors or between a processor and a memory.
The application processor 120 can be coupled to an SD card 130 and a NAND flash memory 140, and interfaces for coupling the memories 130 and 140. In other words, the application processor 120 operates the plurality of memory interfaces as necessary to store multimedia data in any of the memories or to read and playback the stored data.
Referring to FIG. 2, the application processor 120 comprises a processing unit 210, a bus controller 220, a first memory controller 230, and a second memory controller.
The processing unit 210 performs predetermined functions (e.g. MPEG4, 3-D graphics, and camera), designed to be performed by the application processor 120. The processing unit 210 also controls the bus controller 220 by interpreting instructions (including information on which interface to use) received from the main processor 110 and delivering the instruction to the bus controller. The processing unit 210 can be, for example, a 32-bit processor.
The bus controller 220 performs internal bus control such that the first memory controller 230 or the second memory controller 240 is operated by the control of the processing unit 210.
The first memory controller 230 performs data and/or information communication with the SD card 130 through the first memory interface. Usually, a 9-pin interface is used for the first memory interface, which is in the application processor, for coupling to the SD card 130. The 9-pin interface is structured with 4 data signal pins (i.e. SD DAT0, SD DAT1, SD DAT2, and SD DAT3) and 5 control signal pins (i.e. CLK signal, Command signal, Card Detect signal, Power Control signal, and Write Protect signal).
The second memory controller 240 performs data and/or information communication with the NAND flash memory 140 through the second memory interface. Usually, a 14-pin interface is used for the second memory interface, which is in the application processor, for coupling to the NAND flash memory 140. The 14-pin interface is structured with 8 data signal pins (i.e. NF Data0, NF Data1, NF Data2, NF Data3, NF Data4, NF Data5, NF Data6, and NF Data7) and 6 control signal pins (i.e. CS (Chip Select) signal, CLE (Command Latch Enable) signal, ALE (Address Latch Enable) signal, REN (Read Enable) signal, WEN (Write Enable) signal, and WP (Write Protection) signal).
Since the conventional device has to have all memory interfaces that can be coupled, a total of 23 pins (9 pins for the SD card 130 and 14 pins for the NAND flash memory 140) are needed in the case illustrated by FIGS. 1 and 2.
In most devices, however, the application processor 120 does not access a plurality of memories simultaneously. Rather, the application processor 120 alternately accesses one memory at a time. Although the main processor 110 attempts to access the SD card 130 or the NAND flash memory 140, the main processor 110 never accesses the two memories at the same time. Considering this, the application processor 120 does not need to have 2 memory interfaces, and having 2 memory interfaces would be a waste of resource.
Moreover, have 2 memory interfaces causes an increase in physical size, and consequently a cause for increased price.